Humidity control and ventilation devices known in the art ventilate rooms and control humidity of the rooms. PATENT DOCUMENT 1 discloses one of such humidity control and ventilation devices. The humidity control and ventilation device includes an air supply fan and an exhaust fan, and ventilates a room. In other words, the humidity control and ventilation device causes the air supply fan to supply outdoor air into a room, and simultaneously causes the exhaust fan to exhaust room air from the room. Furthermore, this humidity control and ventilation device includes a refrigerant circuit (humidity controller) to which an adsorption heat exchanger is connected, and controls humidity of the room, i.e., dehumidifies or humidifies the room.
Specifically, when the humidity control and ventilation device operates in a dehumidification mode, moisture in the air is adsorbed onto an adsorbent of the adsorption heat exchanger acting as an evaporator. Thus, such dehumidified air is supplied into the room. In addition, when the humidity control and ventilation device operates in a humidification mode, the moisture desorbs from the adsorbent of the adsorption heat exchanger acting as a condenser. Then such desorbing moisture is released into the air. Thus, the humidified air is supplied into the room.
Moreover, the humidity control and ventilation device disclosed in PATENT DOCUMENT 1 controls an airflow rate to be constant to keep a ventilation air volume (supply airflow rate and exhaust airflow rate) of the room optimized. This constant airflow rate control involves adjusting rotation speeds of the air supply fan and the exhaust fan such that the airflow rates of the air supply fan and the exhaust fan are brought close to predetermined target airflow rates of the fans.